Electronic flash lamps are high-pressure discharge lamps, filled with xenon or krypton, for the pulse operation. They consist of a glass or silica glass tube, in whose ends the power lead-ins (anode, cathode) are sealed. The unheated cathode contains emitter materials to reduce the electron work function, in general cesium and barium oxide. The service life of a flash lamp is determined by the decrease of its light efficiency, which is caused by tinting the tube, probably by evaporated electrode material. The higher the flash output of an electronic flash lamp (with the same construction), the shorter the service life.
Since the use of the silica glass tube for the production of flash lamps is expensive, the majority of electronic flash lamps are produced from borosilicate glasses, since these glasses, in comparison with the silica glass, are more reasonably priced and exhibit a simpler glass processibility and a good matching of the seal to the metal of the glass bushing.
It is desirable within the art to obtain a borosilicate glass that makes possible the production of electronic flash lamps with a longer service life and/or higher flash output.